Jet stream models help inform US offshore wind development

Date:
February 7, 2022
Source:
Cornell University
Summary:
With the federal government planning to hold the largest sale of
offshore wind farm leases in the nation's history, a new study could
help inform the development of offshore wind farms by providing
detailed models characterizing the frequency, intensity and height
of low-level jet streams over the U.S. Atlantic coastal zone.



FULL STORY ==========================================================================
With the federal government planning to hold the largest sale of offshore
wind farm leases in the nation's history, a new Cornell University study
could help inform the development of offshore wind farms by providing
detailed models characterizing the frequency, intensity and height of
low-level jet streams over the U.S. Atlantic coastal zone.


==========================================================================
The research, "Occurrence of Low-Level Jets Over the Eastern U.S. Coastal
Zone at Heights Relevant to Wind Energy," published in the journal
Energies. The study finds that jet streams do occur low enough to
reach wind turbine rotor planes at planned wind farms offshore from the
U.S. East Coast, according to co-author Jeanie Aird, doctoral student
in the Barthelmie Wind Energy Laboratory at Cornell.

Low-level jets -- fast-moving currents of air in the lowest 2
kilometers of the atmosphere -- can have pros and cons for wind
turbines. They usually result in an increase in wind speed which can
improve turbine performance, such as power output, but they can also
increase the loads on turbine blades and towers with higher wind shear
and turbulence. Understanding their occurrence is important for planning
wind turbine longevity and power production.

Aird analyzed two years of simulations from the Weather Research and Forecasting (WRF) model provided by Sara C. Pryor, professor in the
Department of Earth and Atmospheric Sciences at Cornell. She found that low-level jets occur more frequently at the offshore wind energy lease
areas south of Massachusetts than those in the New York Bight (stretching roughly from coastal New Jersey to eastern Long Island) and further south.

"Our study specifically focuses on low-level jets that occur with maxima
at approximately 500 meters or below," Aird said, "since at lower heights
they are more likely to interact with wind turbines." Aird found that
the low-level jets can occur at approximately 150 meters above sea level,
which means that they are likely to interact with offshore wind turbines planned for the U.S. East Coast. For example, turbines selected for the Vineyard Wind farm off the coast of Massachusetts have a hub height of
140 meters.

"Our analysis provides maps of low-level jet occurrence showing these
phenomena occur up to 12% of the time in the late spring and early summer
when there are strong horizontal temperature gradients," Aird said. "We
hope this research will assist offshore wind farm developers and we are
working to develop a predictive method for low-level jet occurrence."
Prior to this research there was uncertainty about how frequently
low-level jets would occur in this area, or their speeds and heights,
due to a relative lack of wind climatology measurements for the East
Coast. This study is unique in that the team utilized two years of high-resolution WRF data over a wide geographical domain, covering 13
of the 16 planned offshore lease areas to analyze the low-level jets.

Aird co-authored the paper with Pryor; Rebecca Barthelmie, professor
in the Sibley School of Mechanical and Aerospace Engineering; and
postdoctoral researcher Tristan Shepherd.

The research was funded by the U.S. Department of Energy, the National
Science Foundation and the New York State Energy Research and Development Authority through the National Offshore Wind Research and Development consortium.

========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Eric Laine, courtesy of the Cornell Chronicle. Note: Content may be
edited for style and length.


========================================================================== Journal Reference:
1. Jeanie A. Aird, Rebecca J. Barthelmie, Tristan J. Shepherd, Sara C.

Pryor. Occurrence of Low-Level Jets over the Eastern U.S. Coastal
Zone at Heights Relevant to Wind Energy. Energies, 2022; 15 (2):
445 DOI: 10.3390/en15020445 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/02/220207124808.htm

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